fs file open for read|write

[xinkiknix]

Board

ESP32

Device Description

ESP32 NodeMCU

Hardware Configuration

na

Version

v2.0.2

IDE Name

Arduino IDE

Operating System

Windows 10

Flash frequency

40

PSRAM enabled

yes

Upload speed

115200

Description

I can not position in a file (Seek) and overwrite a portion. There is no option in FS for RW (O_RDWR or FREAD|FWRITE)
I can only open for FILE_READ, FILE_WRITE, FILE_APPEND.

Sketch

File file = fs.open(path, O_RDWR);

Debug Message

\appdata\local\arduino15\packages\esp32\tools\xtensa-esp32-elf-gcc\gcc8_4_0-esp-2021r2\xtensa-esp32-elf\sys-include\sys\_default_fcntl.h:50: note: it was later defined here
 #define O_RDWR  2  /* +1 == FREAD|FWRITE */

Other Steps to Reproduce

No response

I have checked existing issues, online documentation and the Troubleshooting Guide

• I confirm I have checked existing issues, online documentation and Troubleshooting guide.

[VojtechBartoska]

Hello, can you please retest this on v2.0.3-rc1?

[xinkiknix]

I get the same message with version 2.0.3-rc1.
in FS.h mode is still defined/limited as/to
`namespace fs
{

#define FILE_READ "r"
#define FILE_WRITE "w"
#define FILE_APPEND "a"
`

[VojtechBartoska]

Thanks for testing @xinkiknix, are you able to propose PR?

[xinkiknix]

PR?

[igrr]

There is no option in FS for RW (O_RDWR or FREAD|FWRITE)

@xinkiknix When calling FS.open, you can pass any of the file open modes which you can normally pass to C fopen function. Please see its docs here: https://en.cppreference.com/w/c/io/fopen.
Depending on the desired behavior you can use "r+" or "a+" mode.

[xinkiknix]

Thanks, for the update, but then why are there these definitions?
`namespace fs
{

#define FILE_READ "r"
#define FILE_WRITE "w"
#define FILE_APPEND "a"`
?

[lbernstone]

Those defines are legacies from Arduino's SD.h. ESP32 has POSIX compatibility under the covers, so provides emulated Arduino behaviors.

[johnboiles]

I don't think it's safe to use rw in the Arduino APIs. For example in this code if((mode && mode[0] != 'r') && (!create)){ it will only create the file if the first character of the const char *mode is not 'r'. So it will fail to create a file if the mode is specified as 'rw'.

[demosglok]

I don't think it's safe to use rw in the Arduino APIs. For example in this code if((mode && mode[0] != 'r') && (!create)){ it will only create the file if the first character of the const char *mode is not 'r'. So it will fail to create a file if the mode is specified as 'rw'.

try "a+" and "w+". i don't know about "rw", only "a+", "r+", "w+" and I suppose "r+" shouldn't create file, while "w+" and "a+" should

[johnboiles]

Ah yeah rw isn't a real mode I guess. I wanted w+. My bad!

[Parsaabasi]

Hi everyone,

Seems like this issue is resolved. I close it for now.

In case the same issue occurs, or you would need to discuss it further, please reopen it and we will revisit it.

Thanks